US20170284497A1 - Shock absorber - Google Patents
Shock absorberDownload PDFInfo
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- US20170284497A1 US20170284497A1US15/434,633US201715434633AUS2017284497A1US 20170284497 A1US20170284497 A1US 20170284497A1US 201715434633 AUS201715434633 AUS 201715434633AUS 2017284497 A1US2017284497 A1US 2017284497A1
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- 230000035939shockEffects0.000titleclaimsabstractdescription60
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- 230000006835compressionEffects0.000description3
- 238000007906compressionMethods0.000description3
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- 230000000994depressogenic effectEffects0.000description1
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Classifications
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/34—Special valve constructions; Shape or construction of throttling passages
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
- B62K25/00—Axle suspensions
- B62K25/04—Axle suspensions for mounting axles resiliently on cycle frame or fork
- B62K25/28—Axle suspensions for mounting axles resiliently on cycle frame or fork with pivoted chain-stay
- B62K25/283—Axle suspensions for mounting axles resiliently on cycle frame or fork with pivoted chain-stay for cycles without a pedal crank, e.g. motorcycles
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/10—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using liquid only; using a fluid of which the nature is immaterial
- F16F9/14—Devices with one or more members, e.g. pistons, vanes, moving to and fro in chambers and using throttling effect
- F16F9/16—Devices with one or more members, e.g. pistons, vanes, moving to and fro in chambers and using throttling effect involving only straight-line movement of the effective parts
- F16F9/18—Devices with one or more members, e.g. pistons, vanes, moving to and fro in chambers and using throttling effect involving only straight-line movement of the effective parts with a closed cylinder and a piston separating two or more working spaces therein
- F16F9/185—Bitubular units
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/3207—Constructional features
- F16F9/3235—Constructional features of cylinders
- F16F9/3257—Constructional features of cylinders in twin-tube type devices
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
- B62K2201/00—Springs used in cycle frames or parts thereof
- B62K2201/04—Helical springs
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/06—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using both gas and liquid
- F16F9/062—Bi-tubular units
Definitions
- the present inventionrelates to a shock absorber.
- a hydraulic shock absorber for motorcyclesincludes a cylinder provided in a case in which oil is sealed, a piston provided so as to be slidable in the cylinder, a rod connected to the piston so as to extend outside the cylinder, and a damping force generating unit that controls the flow of oil occurring when the piston slides in the cylinder, to generate damping force.
- a hydraulic shock absorberis provided between a vehicle body and a wheel of a motorcycle in a state in which the case is connected to the wheel side or the vehicle body side and the rod is connected to the vehicle body side or the wheel side.
- JP-2011-012806-Adiscloses a configuration of a damping force generating unit which includes a compression-side valve provided in a compression-side passage through which oil flows when a piston moves to a compression side in a cylinder and an extension-side valve provided in an extension-side passage through which oil flows when the piston moves to an extension side in the cylinder.
- the damping force generating unitcommunicates with a subtank that stores oil, on a downstream side of the compression-side valve and the extension-side valve.
- the pistonslides in the cylinder of the case when the wheels move up and down in relation to the vehicle body during traveling of a motorcycle.
- oil compressed by the pistonflows into the compression-side passage and the passage is narrowed by the compression-side valve of the damping force generating unit whereby damping force is generated.
- the compression-side valve and the extension-side valve of the damping force generating unitare formed by a piston body having a port into which oil flows from the compression-side passage or the extension-side passage, and a thin sheet-shaped valve provided on one surface side of the piston body to block the port.
- the valveelastically deforms according to the pressure of the oil in a direction of being separated from the surface of the piston body and the oil passes through a gap between the valve and the piston body.
- the passage of the oilis narrowed by the gap between the valve and the piston body, and the damping force is generated as a result.
- One object of the present inventionis to provide a shock absorber capable of reliably exhibiting its original damping characteristics even when oil flows at a high flow speed.
- a shock absorberincludes: a cylinder which has an outer tube and an inner tube provided on an inner side of the outer tube in a radial direction at an interval from the outer tube, and in which oil is sealed; a piston rod of which one end is inserted into the cylinder and the other end is extended outside the cylinder; a piston which is connected to the one end of the piston rod and is provided in the inner tube so as to be slidable along a central axis direction of the inner tube, and which partitions an inner space of the inner tube into a rod-side oil chamber closer to the piston rod and a piston-side oil chamber on an opposite side to the piston rod; a damping force generating unit which controls the flow of the oil occurring when the piston slides in the inner tube according to a displacement of the piston rod, to generate damping force; and a reservoir that compensates the oil according to a change in advancement volume of the piston rod into the cylinder.
- the shock absorberfurther includes: a reservoir communication path through which the damping force generating unit and the reservoir communicate with each other; a compression-side communication path through which the piston-side oil chamber and the damping force generating unit communicate with each other; and a compression-side port which is provided in the damping force generating unit, into which the oil flows from the compression-side communication path, and which has a compression-side valve that generates the damping force.
- a cross-sectional area of the reservoir communication pathis smaller than a cross-sectional area of the compression-side port.
- shock absorberAs described above, it is possible to reliably exhibit its original damping characteristics even when oil flows at a high flow speed.
- FIG. 1is a front view illustrating an entire configuration of a shock absorber according to an embodiment
- FIG. 2is a side view of the shock absorber when seen from a different angle
- FIG. 3is a cross-sectional view illustrating an entire configuration of the shock absorber
- FIG. 4is an enlarged cross-sectional view of the shock absorber illustrated in FIG. 3 ;
- FIG. 5is a cross-sectional view illustrating a damping force generator provided in the shock absorber
- FIG. 6is a perspective view illustrating a piston member that forms an extension-side piston and a compression-side piston
- FIG. 7is a diagram schematically illustrating a configuration of the shock absorber
- FIG. 8is a diagram conceptually illustrating a flow speed distribution of oil when an excessive input acts on the shock absorber in a compression-side cycle and oil flows at a high speed;
- FIG. 9is a diagram illustrating damping characteristics when an excessive input acts on the shock absorber in a compression-side cycle and oil flows at a high speed.
- FIG. 1is a front view illustrating an entire configuration of a shock absorber according to an embodiment.
- FIG. 2is a side view of the shock absorber when seen from a different angle.
- FIG. 3is a cross-sectional view illustrating an entire configuration of the shock absorber.
- FIG. 4is an enlarged cross-sectional view of the shock absorber illustrated in FIG. 3 .
- a shock absorber 10is provided between a vehicle body of a motorcycle and a rear wheel supporting portion that supports the rear wheel so as to absorb impact or vibration input from the rear wheel.
- the shock absorber 10extends in an up-down direction, for example, a vehicle body-side attachment member 10 t provided at an upper end of the shock absorber 10 is connected to a vehicle body side, and a vehicle shaft-side attachment member 10 b provided at a lower end of the shock absorber 10 is connected to a rear wheel side.
- the present inventiondoes not exclude a case in which the shock absorber 10 is provided so as to extend in a lateral direction (approximately a horizontal direction), for example.
- the shock absorber 10includes a cylinder 11 , a piston 12 (see FIG. 3 ), a piston rod 13 , a reservoir 30 , a damping force generator (a damping force generating unit) 40 , and a spring 14 .
- the cylinder 11includes an inner tube 20 and an outer tube 21 that form a concentric double-wall tube.
- the outer diameter of the inner tube 20is formed to be a predetermined size smaller than the inner diameter of the outer tube 21 . In this way, a cylindrical annular passage 101 is formed between the inner tube 20 and the outer tube 21 .
- a damper case 15 in which the vehicle body-side attachment member 10 t is providedis disposed on an upper end side of the shock absorber 10 .
- a cylindrical cylinder holding portion 16 extending toward the cylinder 11is provided in the damper case 15 .
- the outer tube 21is held in a state in which an upper end 21 t of the outer tube 21 is inserted in the cylinder holding portion 16 .
- the inner tube 20is held in a state in which an upper end 20 t of the inner tube 20 extends upward further than the upper end 21 t of the outer tube 21 and is inserted into an inner tube holding recess 18 formed in the damper case 15 .
- the inner tube holding recess 18has such an inner diameter that the upper end 20 t of the inner tube 20 is inserted in the inner tube holding recess 18 .
- the inner tube holding recess 18has an abutting surface 18 t on which the upper end 20 t of the inner tube 20 abuts and the inner tube holding recess 18 fixes the inner tube 20 in a state in which movement toward the upper side (toward the vehicle body-side attachment member 10 t ) of the inner tube 20 is restrained.
- the outer tube 21has the upper end 21 t , positioned closer to the piston rod 13 , which is disposed on the lower side of the upper end 20 t of the inner tube 20 .
- the outer tube 21is formed so that the lower end 21 b thereof protrudes downward further than the lower end 20 b of the inner tube 20 to a predetermined extent.
- a rod guide 25is provided on the inner side of the lower end 21 b of the outer tube 21 .
- the rod guide 25includes a plate portion 25 p that makes contact with an inner circumferential surface of the outer tube 21 to block the inner side of the lower end 21 b of the outer tube 21 and a tubular portion 25 t that extends toward the damper case 15 from the upper surface of the plate portion 25 p .
- the plate portion 25 p and the tubular portion 25 tare integrated with each other.
- the tubular portion 25 t of the rod guide 25is inserted in the lower end 20 b of the inner tube 20 to thereby hold the lower end 20 b of the inner tube 20 so as to be immovable in a direction crossing the central axis thereof.
- the plate portion 25 p of the rod guide 25blocks the annular passage 101 between the outer tube 21 and the lower end 20 b of the inner tube 20 .
- the rod guide 25has an insertion hole 25 h which passes through the plate portion 25 p and the tubular portion 25 t and through which the piston rod 13 is inserted so that the piston rod 13 is guided so as to be slidable in the central axis direction.
- a rebound rubber 26which absorbs the impact of the piston 12 colliding, is provided on the inner side of the tubular portion 25 t of the rod guide 25 .
- the piston 12is connected to an upper end (one end) 13 a of the piston rod 13 by a nut 27 .
- the piston 12is provided on the inner side of the inner tube 20 of the cylinder 11 together with the piston rod 13 so as to be slidable along the central axis direction (the up-down direction) of the inner tube 20 .
- the piston 12partitions the inner space of the inner tube 20 of the cylinder 11 into a piston-side oil chamber S 1 formed closer to the damper case 15 on the opposite side to the piston rod 13 and a rod-side oil chamber S 2 formed closer to the piston rod 13 .
- the piston rod 13 of which the upper end 13 a is connected to the piston 12extends downward along the central axis direction of the inner tube 20 , passes through the rod guide 25 , and protrudes outside the cylinder 11 .
- the vehicle shaft-side attachment member 10 bis provided at the lower end 13 b of the piston rod 13 .
- a bump rubber 28 for preventing full compression of the shock absorber 10is provided on the vehicle shaft-side attachment member 10 b closer to the cylinder 11 in a state of being inserted in the piston rod 13 .
- a compression-side communication path 102 having one open endis formed in the damper case 15 at a position facing the opening of the upper end 20 t of the inner tube 20 .
- the compression-side communication path 102allows the piston-side oil chamber S 1 to communicate with a first oil chamber S 11 (see FIG. 5 ) of the damping force generator 40 to be described later.
- a plurality of oil holes 103is formed in the lower end 20 b of the inner tube 20 at intervals in the circumferential direction. Due to these oil holes 103 , the rod-side oil chamber S 2 and the annular passage 101 communicate with each other.
- An extension-side communication path 105 having one open endis formed in the damper case 15 on the upper side of the upper end 21 t of the outer tube 21 .
- the extension-side communication path 105allows the annular passage 101 to communicate with a third oil chamber S 13 (see FIG. 5 ) of the damping force generator 40 to be described later.
- a reservoir 30is formed integrally with the damper case 15 and has a cylindrical form, for example, and a bag-shaped bladder 31 is provided therein.
- the bladder 31is formed in a bag form using an elastic member such as rubber and can expand and contract. Gas such as air is filled in the bladder 31 .
- a space on the outer side of the bladder 31 in the reservoir 30is configured as an oil storage chamber S 3 and communicates with a second oil chamber S 12 (see FIG. 5 ) of the damping force generator 40 to be described later through a reservoir communication path 107 .
- Oil which is fluidis filled in the piston-side oil chamber S 1 and the rod-side oil chamber S 2 in the above-described cylinder 11 , the annular passage 101 between the inner tube 20 and the outer tube 21 , the oil storage chamber S 3 in the reservoir 30 , and the damping force generator 40 to be described later.
- FIG. 5is a cross-sectional view illustrating the damping force generator provided in the damper case.
- the damping force generator 40is configured so that a damper unit 41 is detachably attached to a damper cylinder 29 having a bottomed cylindrical form, formed integrally with the damper case 15 .
- the damper unit 41generally has a columnar form and mainly includes a holder member 42 , an outer cap 43 , a main damper 60 , and a damping adjustment portion 80 .
- the holder member 42integrally has a shaft portion 45 formed in a predetermined length portion c closer to one end 42 a and having a fixed outer diameter, and a large diameter portion 46 formed closer to the other end 42 b and having a larger outer diameter than the shaft portion 45 .
- a recess 47 depressed from the other end 42 b side toward one end 42 a sideis formed in the large diameter portion 46 .
- a central hole 48 that is open to one end 42 a and the recess 47is formed in the holder member 42 continuously in the direction of the central axis C of the shaft portion 45 .
- a plurality of holes 46 h through which the recess 47 on the inner side in the radial direction communicates with the outer side in the radial directionis formed in the large diameter portion 46 at intervals in the circumferential direction.
- the outer cap 43has a ring form is screwed and attached to the outer circumferential surface of the large diameter portion 46 .
- the outer cap 43is provided so as to block an opening 29 a of the damper cylinder 29 , and movement of the outer cap 43 in a direction of being removed from the damper cylinder 29 is restricted by a C-ring 49 attached to the inner circumferential surface of the opening 29 a.
- a compression-side outlet check valve 61In the main damper 60 , a compression-side outlet check valve 61 , an extension-side piston 62 , an extension-side damping valve 63 , an intermediate member 64 , a compression-side valve 65 , a compression-side piston 66 , an extension-side outlet check valve 67 , and a stopper plate 68 are sequentially arranged from the large diameter portion 46 side of the holder member 42 to the one end 42 a side thereof.
- the compression-side outlet check valve 61 , the extension-side piston 62 , the extension-side damping valve 63 , the intermediate member 64 , the compression-side valve 65 , the compression-side piston 66 , the extension-side outlet check valve 67 , and the stopper plate 68are formed in a ring form, and the shaft portion 45 of the holder member 42 is inserted through the central portion of these components.
- a plurality of extension-side inlet ports (extension-side ports) 62 t and a plurality of compression-side outlet ports 62 care alternately formed in the extension-side piston 62 along the circumferential direction.
- the extension-side inlet port 62 t and the compression-side outlet port 62 care formed so as to pass through the extension-side piston 62 in the direction of the central axis C.
- the extension-side damping valve 63is provided so as to block an outlet of the extension-side inlet port 62 t closer to the intermediate member 64 .
- the extension-side damping valve 63is formed by stacking a plurality of disc valves 63 v.
- the compression-side outlet check valve 61is formed of a disc valve 61 v and is provided so as to block an outlet of the compression-side outlet port 62 c closer to the large diameter portion 46 .
- a plurality of compression-side inlet ports (compression-side ports) 66 c and a plurality of extension-side outlet ports 66 tare alternately formed in the compression-side piston 66 along the circumferential direction.
- the compression-side inlet port 66 c and the extension-side outlet port 66 tare formed so as to pass through the compression-side piston 66 in the direction of the central axis C.
- the compression-side valve 65is provided so as to block an outlet of the compression-side inlet port 66 c closer to the intermediate member 64 .
- the compression-side valve 65is formed by stacking a plurality of disc valves 65 v.
- the extension-side outlet check valve 67is formed of a disc valve 67 v and is provided so as to block an outlet of the extension-side outlet port 66 t closer to the stopper plate 68 .
- the intermediate member 64is disposed between the extension-side damping valve 63 and the compression-side valve 65 .
- a plurality of passages 64 h through which the inner side in the radial direction communicates with the outer side in the radial directionis formed in the intermediate member 64 continuously in the radial direction at intervals in the circumferential direction.
- a passage 70 extending from the central hole 48 toward the outer side in the radial directionis formed in the shaft portion 45 of the holder member 42 at a position communicating with the respective passages 64 h of the intermediate member 64 .
- the extension-side damping valve 63 and the compression-side valve 65are configured to block the compression-side inlet port 66 c and the extension-side inlet port 62 t to block the flow of oil at normal times.
- the extension-side damping valve 63 and the compression-side valve 65are bent according to the pressure of oil passing through the compression-side inlet port 66 c and the extension-side inlet port 62 t and generate damping force when oil passes through the gap between the compression-side inlet port 66 c and the extension-side inlet port 62 t .
- the extension-side damping valve 63 and the compression-side valve 65adjust the generated damping force by adjusting the number of disc valves 63 v and 65 v.
- the compression-side outlet check valve 61 and the extension-side outlet check valve 67block the flow of oil by blocking the compression-side outlet port 62 c and the extension-side outlet port 66 t at normal times and are bent according to the pressure of the oil passing through the compression-side outlet port 62 c and the extension-side outlet port 66 t to circulate oil.
- the stopper plate 68is disposed closer to one end 42 a of the shaft portion 45 of the holder member 42 in relation to the extension-side outlet check valve 67 .
- a nut member 69is screwed to a screw groove 45 n formed at one end 42 a of the shaft portion 45 , and the compression-side outlet check valve 61 , the extension-side piston 62 , the extension-side damping valve 63 , the intermediate member 64 , the compression-side valve 65 , the compression-side piston 66 , the extension-side outlet check valve 67 , and the stopper plate 68 are sandwiched between the nut member 69 and the large diameter portion 46 of the holder member 42 .
- the damping adjustment portion 80includes a compression-side adjustment valve 81 , a compression-side adjuster 82 , an extension-side adjustment valve 83 , and an extension-side adjuster 84 .
- the compression-side adjustment valve 81has a distal end inserted into the central hole 48 from the recess 47 formed in the large diameter portion 46 of the holder member 42 , and has a base end (the other end 42 b ) coupled with a disc-shaped end piece 81 b within the recess 47 .
- the compression-side adjustment valve 81has an outer diameter smaller than the inner diameter of the central hole 48 . Due to this, a gap passage 85 is formed between the inner circumferential surface of the central hole 48 and the outer circumferential surface of the compression-side adjustment valve 81 . Moreover, the compression-side adjustment valve 81 has a valve portion 81 v which is provided at a distal end (one end 42 a ) side and of which the outer diameter decreases gradually toward the distal end. A throttle portion 71 of which the inner diameter is narrowed is formed in the central hole 48 closer to one end 42 a of the holder member 42 than the passage 70 , and the valve portion 81 v is inserted in the throttle portion 71 .
- the compression-side adjuster 82is held on an inner cap 87 attached to the inner side of the outer cap 43 so as to be rotatable around the central axis.
- the compression-side adjuster 82extends into the recess 47 and engages with the end piece 81 b .
- a base portion 82 a of the compression-side adjuster 82is exposed to the outer side from the inner cap 87 .
- the end piece 81 badvances and retracts in the direction of the central axis C along the compression-side adjuster 82 .
- the valve portion 81 v of the compression-side adjustment valve 81advances and retracts in relation to the throttle portion 71 to increase and decrease the gap between the throttle portion 71 and the valve portion 81 v.
- the extension-side adjustment valve 83includes a tubular valve portion 83 v which is provided in the recess 47 so as to extend toward an opening closer to the recess 47 of the central hole 48 .
- the valve portion 83 vis integrated with the extension-side adjustment valve 83 .
- the compression-side adjustment valve 81is inserted into the extension-side adjustment valve 83 .
- the extension-side adjuster 84is held on the inner cap 87 attached to the inner side of the outer cap 43 so as to be rotatable around the central axis.
- the extension-side adjuster 84extends into the recess 47 and engages with the extension-side adjustment valve 83 .
- a base portion 84 a of the extension-side adjuster 84is exposed to the outer side from the inner cap 87 .
- the extension-side adjustment valve 83advances and retracts in the direction of the central axis C.
- the valve portion 83 v of the extension-side adjustment valve 83advances and retracts in relation to the opening of the central hole 48 to increase and decrease the gap between the valve portion 83 v and the gap passage 85 .
- the extension-side piston 62 and the compression-side piston 66are formed of a piston member 75 to be described below.
- FIG. 6is a perspective view illustrating a piston member that forms the extension-side piston 62 and the compression-side piston 66 .
- the piston member 75integrally includes inner circumferential walls 75 i , outer circumferential walls 75 o formed on the outer side in the radial direction of the inner circumferential wall 75 i , and a plurality of connection walls 75 w formed at intervals in the circumferential direction so as to extend in the radial direction to connect the inner circumferential walls 75 i and the outer circumferential walls 75 o.
- An insertion hole 75 h in which the shaft portion 45 of the holder member 42 is insertedis formed on the inner side of the inner circumferential walls 75 i.
- a protruding wall 75 m that protrudes toward the outer side in the radial directionis formed on the outer circumferential surface of the outer circumferential wall 75 o continuously in the circumferential direction.
- a sealing ring 76 that abuts on the inner circumferential surface of the damper cylinder 29 to seal the space between the piston member 75 and the inner circumferential surface of the damper cylinder 29is provided on the outer circumferential surface of the protruding wall 75 m.
- a first port 77 and a second port 78are alternately formed in the piston member 75 along the circumferential direction between the inner circumferential wall 75 i and the outer circumferential wall 75 o .
- the first and second ports 77 and 78are formed between the connection walls 75 w , adjacent to each other in the circumferential direction.
- the first and second ports 77 and 78pass in the direction of connecting one end 75 a of the piston member 75 and the other end 75 b .
- the first port 77forms the extension-side inlet port 62 t or the compression-side inlet port 66 c
- the second port 78forms the compression-side outlet port 62 c or the extension-side outlet port 66 t.
- the first port 77has a port inlet 77 a provided closer to one end 75 a and a port outlet 77 b provided closer to the other end 75 b .
- a notch 75 kis formed in the outer circumferential wall 75 o on the side closer to one end 75 a whereby a port inlet opening (a compression-side port inlet portion) 79 A that is open to the outer side in the radial direction is formed in the first port 77 .
- the second port 78has a port inlet 78 a provided closer to the other end 75 b and a port outlet 78 b provided closer to one end 75 a .
- a notch 75 jis formed in the outer circumferential wall 75 o on the side closer to the other end 75 b whereby a port inlet opening (a compression-side outlet port inlet portion) 79 B that is open to the outer side in the radial direction is formed in the second port 78 .
- the inner space of the damper cylinder 29is partitioned into the first oil chamber S 11 , the second oil chamber S 12 , and the third oil chamber S 13 by the sealing ring 76 of the piston member 75 that forms the compression-side piston 66 and the sealing ring 76 of the piston member 75 that forms the extension-side piston 62 .
- the first oil chamber S 11is formed closer to one end 42 a of the holder member 42 than the sealing ring 76 of the compression-side piston 66 and communicates with the piston-side oil chamber S 1 (see FIG. 4 ) through the compression-side communication path 102 .
- the second oil chamber S 12is formed between the sealing ring 76 of the compression-side piston 66 and the sealing ring 76 of the extension-side piston 62 and communicates with the oil storage chamber S 3 (see FIG. 4 ) of the reservoir 30 through the reservoir communication path 107 .
- the third oil chamber S 13is formed between the sealing ring 76 of the extension-side piston 62 and the outer cap 43 and communicates with the annular passage 101 (see FIG. 4 ) of the cylinder 11 through the extension-side communication path 105 .
- the central hole 48 formed in the holder member 42is open to the inner space of the first oil chamber S 11 at one end 42 a of the holder member 42 .
- the passage 64 h formed in the intermediate member 64is open to the inner space of the second oil chamber S 12 .
- the hole 46 h formed in the large diameter portion 46 of the holder member 42is open to the inner space of the third oil chamber S 13 .
- FIG. 7is a diagram schematically illustrating the configuration of the shock absorber described above.
- the oil delivered to the first oil chamber S 11flows into the compression-side inlet port 66 c from the port inlet opening 79 A formed in the compression-side piston 66 of the main damper 60 to push and open the compression-side valve 65 provided on the outlet side of the compression-side inlet port 66 c and flows toward the second oil chamber S 12 .
- the oilpushes and opens the compression-side valve 65 to pass through the gap between the compression-side valve 65 and the outlet of the compression-side inlet port 66 c whereby damping force is generated.
- a portion of the oil delivered to the first oil chamber S 11flows into the central hole 48 open to one end 42 a of the holder member 42 to pass through the gap between the throttle portion 71 and the valve portion 81 v of the compression-side adjustment valve 81 and flows into the second oil chamber S 12 through the passage 70 formed in the shaft portion 45 and the passage 64 h formed in the intermediate member 64 .
- damping forceis generated.
- a portion of the oil flowing into the second oil chamber S 12flows into the oil storage chamber S 3 through the reservoir communication path 107 formed in the damper case 15 in order to compensate for a change in the volume of the piston rod 13 in the cylinder 11 according to the movement of the piston 12 .
- a remaining portion of the oil flowing into the second oil chamber S 12flows into the compression-side outlet port 62 c from the port inlet opening 79 B of the extension-side piston 62 to push and open the compression-side outlet check valve 61 and flows into the third oil chamber S 13 .
- the oil flowing into the third oil chamber S 13flows into the rod-side oil chamber S 2 through the extension-side communication path 105 , the annular passage 101 of the cylinder 11 , and the plurality of oil holes 103 .
- the oil delivered to the third oil chamber S 13flows into the extension-side inlet port 62 t from the port inlet opening 79 A of the extension-side piston 62 to push and open the extension-side damping valve 63 provided on the outlet side of the extension-side inlet port 62 t whereby damping force is generated.
- the oil having passed through the gap between the extension-side inlet port 62 t and the extension-side damping valve 63flows toward the second oil chamber S 12 .
- the oilflows from the oil storage chamber S 3 into the second oil chamber S 12 through the reservoir communication path 107 formed in the damper case 15 in order to compensate for a change in the volume of the piston rod 13 in the cylinder 11 according to the movement of the piston 12 .
- the oil having flowed into the second oil chamber S 12passes through the extension-side outlet port 66 t from the port inlet opening 79 B of the compression-side piston 66 to push and open the extension-side outlet check valve 67 and flows into the first oil chamber S 11 .
- the oil in the first oil chamber S 11is delivered to the piston-side oil chamber S 1 through the compression-side communication path 102 formed in the damper case 15 .
- the cross-sectional area A 0 of the reservoir communication path 107is smaller than the total cross-sectional area A 1 of the plurality of compression-side inlet ports 66 c having the compression-side valve 65 that generates damping force.
- the cross-sectional area A 2 of the compression-side communication path 102is equal to or larger than the cross-sectional area A 1 of the compression-side inlet port 66 c.
- the cross-sectional area A 3 between the compression-side piston 66 and the damper cylinder 29 into which the oil flows from the compression-side communication path 102is equal to or larger than the total cross-sectional area A 1 of the compression-side inlet port 66 c and is equal to or smaller than the cross-sectional area A 2 of the compression-side communication path 102 .
- a total opening area A 4 of the plurality of port inlet openings 79 Ais larger than the total cross-sectional area A 1 of the plurality of compression-side inlet ports 66 c.
- a passage cross-sectional area of a compression-side oil passage systemthat extends from the piston-side oil chamber S 1 to reach the second oil chamber S 12 gradually decreases without increasing in the halfway of the passage. Furthermore, since the cross-sectional area A 0 of the reservoir communication path 107 is smaller than the total cross-sectional area A 1 of the plurality of compression-side inlet ports 66 c , the cross-sectional area A 0 of the reservoir communication path 107 is the smallest.
- the cross-sectional area A 11 of the extension-side communication path 105is larger than the cross-sectional area A 0 of the reservoir communication path 107 .
- the cross-sectional area A 14 between the damper cylinder 29 and the extension-side piston 62is larger than the cross-sectional area A 0 of the reservoir communication path 107 .
- the total cross-sectional area A 15 of the plurality of compression-side outlet ports 62 cis equal to or larger than the cross-sectional area A 14 between the damper cylinder 29 and the extension-side piston 62 .
- the total opening area A 16 of the plurality of port inlet openings 79 Bis equal to or larger than the total cross-sectional area A 15 of the plurality of compression-side outlet ports 62 c.
- the cross-sectional area A 12 of the annular passage 101is equal to or larger than the cross-sectional area A 11 of the extension-side communication path 105 .
- the total cross-sectional area A 13 of the plurality of oil holes 103is equal to or larger than the cross-sectional area A 12 of the annular passage 101 .
- the cross-sectional area A 0 of the reservoir communication path 107 , the total cross-sectional area A 1 of the compression-side inlet port 66 c , the cross-sectional area A 2 of the compression-side communication path 102 , the cross-sectional area A 3 between the damper cylinder 29 and the compression-side piston 66 , the total opening area A 4 of the port inlet openings 79 A, the cross-sectional area A 11 of the extension-side communication path 105 , the cross-sectional area A 14 between the damper cylinder 29 and the extension-side piston 62 , the total cross-sectional area A 15 of the compression-side outlet ports 62 c , and the total opening areas A 16 of the port inlet openings 79 Bare the cross-sectional areas of the smallest-diameter portions of the passages.
- the shock absorber 10 of the present embodimentby setting the cross-sectional area A 0 of the reservoir communication path 107 to be smaller than the cross-sectional area A 1 of the compression-side inlet port 66 c , oil does not easily flow into the reservoir 30 when an excessive input acts during the compression-side operation. In this way, after oil flows from the piston-side oil chamber S 1 to the damping force generator 40 through the compression-side communication path 102 and damping force is generated in the compression-side inlet port 66 c , the oil flows smoothly toward the piston-side oil chamber S 1 . As a result, the shock absorber 10 can exhibit its original damping characteristics even when oil flows at a high flow speed, for example.
- An oil passage system that extends from the piston-side oil chamber S 1 to reach the second oil chamber S 12 in the compression-side operationis configured so that the cross-sectional area A 2 of the compression-side communication path 102 , the cross-sectional area A 3 between the damper cylinder 29 and the compression-side piston 66 , the total opening areas A 4 of the plurality of port inlet openings 79 A, and the total cross-sectional area A 1 of the plurality of compression-side inlet ports 66 c satisfy the relation of A 2 ⁇ A 3 ⁇ A 4 ⁇ A 1 . That is, the passage cross-sectional area of the compression-side oil passage system extending from the piston-side oil chamber S 1 to reach the second oil chamber S 12 gradually decreases without increasing in the halfway of the passage.
- the cross-sectional area A 0 of the reservoir communication path 107is smaller than the total cross-sectional area A 1 of the plurality of compression-side inlet ports 66 c , the cross-sectional area A 0 of the reservoir communication path 107 is the smallest.
- An oil passage systemthat extends from the second oil chamber S 12 to return to the cylinder-side oil chamber S 2 in the compression-side operation is configured so that the cross-sectional area A 0 of the reservoir communication path 107 , the cross-sectional area A 14 between the damper cylinder 29 and the extension-side piston 62 , the total opening area A 16 of the plurality of port inlet openings 79 B, the total cross-sectional area A 15 of the plurality of compression-side outlet ports 62 c , the cross-sectional area A 11 of the extension-side communication path 105 , the cross-sectional area A 12 of the annular passage 101 , and the cross-sectional area A 13 of the oil hole 103 satisfy the relation of A 0 ⁇ A 14 ⁇ A 16 ⁇ A 15 ⁇ A 11 ⁇ A 12 ⁇ A 13 .
- FIG. 8is a diagram conceptually illustrating an oil flow speed distribution when an excessive input acts on the shock absorber in a compression-side cycle and oil flows at a high speed.
- the thickness of an arrowindicates the flow speed of oil.
- the shock absorber 10by configuring the shock absorber 10 so that the cross-sectional area A 0 of the reservoir communication path 107 is the smallest as described above, oil does not easily flow into the reservoir 30 when an excessive input acts during the compression-side operation. In this way, after oil flows from the piston-side oil chamber S 1 into the damping force generator 40 through the compression-side communication path 102 and damping force is generated in the compression-side inlet port 66 c , the oil smoothly flows toward the piston-side oil chamber S 1 through an extension-side passage. As a result, the shock absorber 10 can exhibit its original damping characteristics even when oil flows at a high flow speed.
- FIG. 9is a diagram illustrating damping characteristics as the relation between stroke and load when an excessive input acts on the shock absorber in the compression-side cycle and oil flows at a high speed.
- the damping characteristicsare distorted when the shock absorber operates at a high speed due to an excessive input as indicated by a two-dot chain line in FIG. 9 .
- the shock absorber 10 having the configuration of the present embodimenteven when the shock absorber operates at a high speed due to an excessive input, it is possible to suppress deformation of damping characteristics and to obtain satisfactory damping characteristics.
- shock absorber of the present inventionis not limited to the embodiment described above with reference to the drawings, and various modifications may occur within the technical scope thereof.
- the configuration of the damping adjustment portion 80 provided in the damping force generator 40is not particularly limited, and the damping adjustment portion 80 may be omitted.
- extension-side piston 62 and the compression-side piston 66are formed of the piston member 75 , the present invention is not limited to this. Any one of the extension-side piston 62 and the compression-side piston 66 may be formed alone of the piston member 75 . Moreover, the compression-side inlet port 66 c only may include the port inlet opening 79 A that is open to the outer side in the radial direction.
- the entire configuration of the shock absorber 10can be changed appropriately.
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Abstract
Description
- This application claims priority from Japanese Patent Application No. 2016-069674 filed on Mar. 30, 2016, the entire contents of which are incorporated herein by reference.
- The present invention relates to a shock absorber.
- A hydraulic shock absorber for motorcycles includes a cylinder provided in a case in which oil is sealed, a piston provided so as to be slidable in the cylinder, a rod connected to the piston so as to extend outside the cylinder, and a damping force generating unit that controls the flow of oil occurring when the piston slides in the cylinder, to generate damping force. Such a hydraulic shock absorber is provided between a vehicle body and a wheel of a motorcycle in a state in which the case is connected to the wheel side or the vehicle body side and the rod is connected to the vehicle body side or the wheel side.
- JP-2011-012806-A discloses a configuration of a damping force generating unit which includes a compression-side valve provided in a compression-side passage through which oil flows when a piston moves to a compression side in a cylinder and an extension-side valve provided in an extension-side passage through which oil flows when the piston moves to an extension side in the cylinder. Here, the damping force generating unit communicates with a subtank that stores oil, on a downstream side of the compression-side valve and the extension-side valve.
- In a hydraulic shock absorber having such a configuration, the piston slides in the cylinder of the case when the wheels move up and down in relation to the vehicle body during traveling of a motorcycle. When the piston moves to the compression side in the cylinder, oil compressed by the piston flows into the compression-side passage and the passage is narrowed by the compression-side valve of the damping force generating unit whereby damping force is generated. Moreover, when the piston moves to the extension side in the cylinder, oil flows into the extension-side passage and the passage is narrowed by the extension-side valve of the damping force generating unit whereby damping force is generated.
- The compression-side valve and the extension-side valve of the damping force generating unit are formed by a piston body having a port into which oil flows from the compression-side passage or the extension-side passage, and a thin sheet-shaped valve provided on one surface side of the piston body to block the port. When oil flows from the compression-side passage or the extension-side passage into the port, the valve elastically deforms according to the pressure of the oil in a direction of being separated from the surface of the piston body and the oil passes through a gap between the valve and the piston body. The passage of the oil is narrowed by the gap between the valve and the piston body, and the damping force is generated as a result.
- For example, in a motorcycle for competition such as motocross, when the motorcycle hits on the ground from a jumping state, the wheels are displaced at a high speed of 10 m/s, for example, in relation to the vehicle body. When a displacement at such a high speed is input to the shock absorber, the piston moves at a high speed in the cylinder. As a result, oil flows at a high flow speed in the cylinder, and a large passage resistance is generated in a portion in which damping force is not generated at a low flow speed (for example, a narrowed intermediate portion of the passage through which oil flows toward the gap between the valve and the valve body). As a result, damping force is generated in a portion other than the gap between the valve and the piston body in which damping force is to be generated, and the shock absorber cannot exhibit its original damping characteristics.
- One object of the present invention is to provide a shock absorber capable of reliably exhibiting its original damping characteristics even when oil flows at a high flow speed.
- A shock absorber according to an aspect of the present invention includes: a cylinder which has an outer tube and an inner tube provided on an inner side of the outer tube in a radial direction at an interval from the outer tube, and in which oil is sealed; a piston rod of which one end is inserted into the cylinder and the other end is extended outside the cylinder; a piston which is connected to the one end of the piston rod and is provided in the inner tube so as to be slidable along a central axis direction of the inner tube, and which partitions an inner space of the inner tube into a rod-side oil chamber closer to the piston rod and a piston-side oil chamber on an opposite side to the piston rod; a damping force generating unit which controls the flow of the oil occurring when the piston slides in the inner tube according to a displacement of the piston rod, to generate damping force; and a reservoir that compensates the oil according to a change in advancement volume of the piston rod into the cylinder. The shock absorber further includes: a reservoir communication path through which the damping force generating unit and the reservoir communicate with each other; a compression-side communication path through which the piston-side oil chamber and the damping force generating unit communicate with each other; and a compression-side port which is provided in the damping force generating unit, into which the oil flows from the compression-side communication path, and which has a compression-side valve that generates the damping force. A cross-sectional area of the reservoir communication path is smaller than a cross-sectional area of the compression-side port.
- As described above, by setting the cross-sectional area of the reservoir communication path to be smaller than the cross-sectional area of the compression-side port, oil does not easily flow into the reservoir when an excessive input acts during the compression-side operation. In this way, after the oil pushed by the piston flows from the piston-side oil chamber to the damping force generation unit through the compression-side communication path and damping force is generated in the compression-side port, the oil flows smoothly toward the cylinder-side oil chamber. As a result, the shock absorber can exhibit its original damping characteristics even when oil flows at a high flow speed.
- According to the shock absorber as described above, it is possible to reliably exhibit its original damping characteristics even when oil flows at a high flow speed.
FIG. 1 is a front view illustrating an entire configuration of a shock absorber according to an embodiment;FIG. 2 is a side view of the shock absorber when seen from a different angle;FIG. 3 is a cross-sectional view illustrating an entire configuration of the shock absorber;FIG. 4 is an enlarged cross-sectional view of the shock absorber illustrated inFIG. 3 ;FIG. 5 is a cross-sectional view illustrating a damping force generator provided in the shock absorber;FIG. 6 is a perspective view illustrating a piston member that forms an extension-side piston and a compression-side piston;FIG. 7 is a diagram schematically illustrating a configuration of the shock absorber;FIG. 8 is a diagram conceptually illustrating a flow speed distribution of oil when an excessive input acts on the shock absorber in a compression-side cycle and oil flows at a high speed; andFIG. 9 is a diagram illustrating damping characteristics when an excessive input acts on the shock absorber in a compression-side cycle and oil flows at a high speed.- Hereinafter, an embodiment for implementing a shock absorber will be described with reference to the accompanying drawings. However, the present invention is not limited to this embodiment.
FIG. 1 is a front view illustrating an entire configuration of a shock absorber according to an embodiment.FIG. 2 is a side view of the shock absorber when seen from a different angle.FIG. 3 is a cross-sectional view illustrating an entire configuration of the shock absorber.FIG. 4 is an enlarged cross-sectional view of the shock absorber illustrated inFIG. 3 .- As illustrated in
FIGS. 1 to 3 , ashock absorber 10 is provided between a vehicle body of a motorcycle and a rear wheel supporting portion that supports the rear wheel so as to absorb impact or vibration input from the rear wheel. In the following description, the shock absorber10 extends in an up-down direction, for example, a vehicle body-side attachment member 10tprovided at an upper end of theshock absorber 10 is connected to a vehicle body side, and a vehicle shaft-side attachment member 10bprovided at a lower end of theshock absorber 10 is connected to a rear wheel side. However, the present invention does not exclude a case in which the shock absorber10 is provided so as to extend in a lateral direction (approximately a horizontal direction), for example. - The
shock absorber 10 includes acylinder 11, a piston12 (seeFIG. 3 ), apiston rod 13, areservoir 30, a damping force generator (a damping force generating unit)40, and aspring 14. - As illustrated in
FIGS. 3 and 4 , thecylinder 11 includes aninner tube 20 and anouter tube 21 that form a concentric double-wall tube. - The outer diameter of the
inner tube 20 is formed to be a predetermined size smaller than the inner diameter of theouter tube 21. In this way, a cylindricalannular passage 101 is formed between theinner tube 20 and theouter tube 21. - A
damper case 15 in which the vehicle body-side attachment member 10tis provided is disposed on an upper end side of theshock absorber 10. A cylindricalcylinder holding portion 16 extending toward thecylinder 11 is provided in thedamper case 15. Theouter tube 21 is held in a state in which anupper end 21tof theouter tube 21 is inserted in thecylinder holding portion 16. - As illustrated in
FIG. 4 , theinner tube 20 is held in a state in which anupper end 20tof theinner tube 20 extends upward further than theupper end 21tof theouter tube 21 and is inserted into an innertube holding recess 18 formed in thedamper case 15. The innertube holding recess 18 has such an inner diameter that theupper end 20tof theinner tube 20 is inserted in the innertube holding recess 18. The innertube holding recess 18 has anabutting surface 18ton which theupper end 20tof theinner tube 20 abuts and the innertube holding recess 18 fixes theinner tube 20 in a state in which movement toward the upper side (toward the vehicle body-side attachment member 10t) of theinner tube 20 is restrained. - The
outer tube 21 has theupper end 21t, positioned closer to thepiston rod 13, which is disposed on the lower side of theupper end 20tof theinner tube 20. - Moreover, the
outer tube 21 is formed so that thelower end 21bthereof protrudes downward further than thelower end 20bof theinner tube 20 to a predetermined extent. - A
rod guide 25 is provided on the inner side of thelower end 21bof theouter tube 21. Therod guide 25 includes aplate portion 25pthat makes contact with an inner circumferential surface of theouter tube 21 to block the inner side of thelower end 21bof theouter tube 21 and atubular portion 25tthat extends toward thedamper case 15 from the upper surface of theplate portion 25p. Theplate portion 25pand thetubular portion 25tare integrated with each other. - The
tubular portion 25tof therod guide 25 is inserted in thelower end 20bof theinner tube 20 to thereby hold thelower end 20bof theinner tube 20 so as to be immovable in a direction crossing the central axis thereof. - The
plate portion 25pof therod guide 25 blocks theannular passage 101 between theouter tube 21 and thelower end 20bof theinner tube 20. - Moreover, the
rod guide 25 has aninsertion hole 25hwhich passes through theplate portion 25pand thetubular portion 25tand through which thepiston rod 13 is inserted so that thepiston rod 13 is guided so as to be slidable in the central axis direction. - Furthermore, a
rebound rubber 26, which absorbs the impact of thepiston 12 colliding, is provided on the inner side of thetubular portion 25tof therod guide 25. - The
piston 12 is connected to an upper end (one end)13aof thepiston rod 13 by anut 27. Thepiston 12 is provided on the inner side of theinner tube 20 of thecylinder 11 together with thepiston rod 13 so as to be slidable along the central axis direction (the up-down direction) of theinner tube 20. - The
piston 12 partitions the inner space of theinner tube 20 of thecylinder 11 into a piston-side oil chamber S1 formed closer to thedamper case 15 on the opposite side to thepiston rod 13 and a rod-side oil chamber S2 formed closer to thepiston rod 13. - As illustrated in
FIG. 3 , thepiston rod 13 of which theupper end 13ais connected to thepiston 12 extends downward along the central axis direction of theinner tube 20, passes through therod guide 25, and protrudes outside thecylinder 11. The vehicle shaft-side attachment member 10bis provided at thelower end 13bof thepiston rod 13. Abump rubber 28 for preventing full compression of theshock absorber 10 is provided on the vehicle shaft-side attachment member 10bcloser to thecylinder 11 in a state of being inserted in thepiston rod 13. - A compression-
side communication path 102 having one open end is formed in thedamper case 15 at a position facing the opening of theupper end 20tof theinner tube 20. The compression-side communication path 102 allows the piston-side oil chamber S1 to communicate with a first oil chamber S11 (seeFIG. 5 ) of the dampingforce generator 40 to be described later. - A plurality of
oil holes 103 is formed in thelower end 20bof theinner tube 20 at intervals in the circumferential direction. Due to theseoil holes 103, the rod-side oil chamber S2 and theannular passage 101 communicate with each other. - An extension-
side communication path 105 having one open end is formed in thedamper case 15 on the upper side of theupper end 21tof theouter tube 21. The extension-side communication path 105 allows theannular passage 101 to communicate with a third oil chamber S13 (seeFIG. 5 ) of the dampingforce generator 40 to be described later. - A
reservoir 30 is formed integrally with thedamper case 15 and has a cylindrical form, for example, and a bag-shapedbladder 31 is provided therein. Thebladder 31 is formed in a bag form using an elastic member such as rubber and can expand and contract. Gas such as air is filled in thebladder 31. A space on the outer side of thebladder 31 in thereservoir 30 is configured as an oil storage chamber S3 and communicates with a second oil chamber S12 (seeFIG. 5 ) of the dampingforce generator 40 to be described later through areservoir communication path 107. - Oil which is fluid is filled in the piston-side oil chamber S1 and the rod-side oil chamber S2 in the above-described
cylinder 11, theannular passage 101 between theinner tube 20 and theouter tube 21, the oil storage chamber S3 in thereservoir 30, and the dampingforce generator 40 to be described later. FIG. 5 is a cross-sectional view illustrating the damping force generator provided in the damper case.- As illustrated in
FIG. 5 , the dampingforce generator 40 is configured so that adamper unit 41 is detachably attached to adamper cylinder 29 having a bottomed cylindrical form, formed integrally with thedamper case 15. - The
damper unit 41 generally has a columnar form and mainly includes aholder member 42, anouter cap 43, amain damper 60, and a dampingadjustment portion 80. - The
holder member 42 integrally has ashaft portion 45 formed in a predetermined length portion c closer to oneend 42aand having a fixed outer diameter, and alarge diameter portion 46 formed closer to theother end 42band having a larger outer diameter than theshaft portion 45. Arecess 47 depressed from theother end 42bside toward oneend 42aside is formed in thelarge diameter portion 46. Furthermore, acentral hole 48 that is open to oneend 42aand therecess 47 is formed in theholder member 42 continuously in the direction of the central axis C of theshaft portion 45. - Moreover, a plurality of
holes 46hthrough which therecess 47 on the inner side in the radial direction communicates with the outer side in the radial direction is formed in thelarge diameter portion 46 at intervals in the circumferential direction. - The
outer cap 43 has a ring form is screwed and attached to the outer circumferential surface of thelarge diameter portion 46. Theouter cap 43 is provided so as to block anopening 29aof thedamper cylinder 29, and movement of theouter cap 43 in a direction of being removed from thedamper cylinder 29 is restricted by a C-ring 49 attached to the inner circumferential surface of the opening29a. - In the
main damper 60, a compression-sideoutlet check valve 61, an extension-side piston 62, an extension-side damping valve 63, anintermediate member 64, a compression-side valve 65, a compression-side piston 66, an extension-sideoutlet check valve 67, and astopper plate 68 are sequentially arranged from thelarge diameter portion 46 side of theholder member 42 to the oneend 42aside thereof. The compression-sideoutlet check valve 61, the extension-side piston 62, the extension-side damping valve 63, theintermediate member 64, the compression-side valve 65, the compression-side piston 66, the extension-sideoutlet check valve 67, and thestopper plate 68 are formed in a ring form, and theshaft portion 45 of theholder member 42 is inserted through the central portion of these components. - A plurality of extension-side inlet ports (extension-side ports)62tand a plurality of compression-
side outlet ports 62care alternately formed in the extension-side piston 62 along the circumferential direction. The extension-side inlet port 62tand the compression-side outlet port 62care formed so as to pass through the extension-side piston 62 in the direction of the central axis C. - The extension-
side damping valve 63 is provided so as to block an outlet of the extension-side inlet port 62tcloser to theintermediate member 64. The extension-side damping valve 63 is formed by stacking a plurality ofdisc valves 63v. - The compression-side
outlet check valve 61 is formed of adisc valve 61vand is provided so as to block an outlet of the compression-side outlet port 62ccloser to thelarge diameter portion 46. - A plurality of compression-side inlet ports (compression-side ports)66cand a plurality of extension-
side outlet ports 66tare alternately formed in the compression-side piston 66 along the circumferential direction. The compression-side inlet port 66cand the extension-side outlet port 66tare formed so as to pass through the compression-side piston 66 in the direction of the central axis C. - The compression-
side valve 65 is provided so as to block an outlet of the compression-side inlet port 66ccloser to theintermediate member 64. The compression-side valve 65 is formed by stacking a plurality ofdisc valves 65v. - The extension-side
outlet check valve 67 is formed of adisc valve 67vand is provided so as to block an outlet of the extension-side outlet port 66tcloser to thestopper plate 68. - The
intermediate member 64 is disposed between the extension-side damping valve 63 and the compression-side valve 65. A plurality ofpassages 64hthrough which the inner side in the radial direction communicates with the outer side in the radial direction is formed in theintermediate member 64 continuously in the radial direction at intervals in the circumferential direction. Apassage 70 extending from thecentral hole 48 toward the outer side in the radial direction is formed in theshaft portion 45 of theholder member 42 at a position communicating with therespective passages 64hof theintermediate member 64. - The extension-
side damping valve 63 and the compression-side valve 65 are configured to block the compression-side inlet port 66cand the extension-side inlet port 62tto block the flow of oil at normal times. The extension-side damping valve 63 and the compression-side valve 65 are bent according to the pressure of oil passing through the compression-side inlet port 66cand the extension-side inlet port 62tand generate damping force when oil passes through the gap between the compression-side inlet port 66cand the extension-side inlet port 62t. The extension-side damping valve 63 and the compression-side valve 65 adjust the generated damping force by adjusting the number ofdisc valves - The compression-side
outlet check valve 61 and the extension-sideoutlet check valve 67 block the flow of oil by blocking the compression-side outlet port 62cand the extension-side outlet port 66tat normal times and are bent according to the pressure of the oil passing through the compression-side outlet port 62cand the extension-side outlet port 66tto circulate oil. - The
stopper plate 68 is disposed closer to oneend 42aof theshaft portion 45 of theholder member 42 in relation to the extension-sideoutlet check valve 67. - A
nut member 69 is screwed to ascrew groove 45nformed at oneend 42aof theshaft portion 45, and the compression-sideoutlet check valve 61, the extension-side piston 62, the extension-side damping valve 63, theintermediate member 64, the compression-side valve 65, the compression-side piston 66, the extension-sideoutlet check valve 67, and thestopper plate 68 are sandwiched between thenut member 69 and thelarge diameter portion 46 of theholder member 42. - The damping
adjustment portion 80 includes a compression-side adjustment valve 81, a compression-side adjuster 82, an extension-side adjustment valve 83, and an extension-side adjuster 84. - The compression-
side adjustment valve 81 has a distal end inserted into thecentral hole 48 from therecess 47 formed in thelarge diameter portion 46 of theholder member 42, and has a base end (theother end 42b) coupled with a disc-shapedend piece 81bwithin therecess 47. - The compression-
side adjustment valve 81 has an outer diameter smaller than the inner diameter of thecentral hole 48. Due to this, agap passage 85 is formed between the inner circumferential surface of thecentral hole 48 and the outer circumferential surface of the compression-side adjustment valve 81. Moreover, the compression-side adjustment valve 81 has avalve portion 81vwhich is provided at a distal end (oneend 42a) side and of which the outer diameter decreases gradually toward the distal end. Athrottle portion 71 of which the inner diameter is narrowed is formed in thecentral hole 48 closer to oneend 42aof theholder member 42 than thepassage 70, and thevalve portion 81vis inserted in thethrottle portion 71. - The compression-
side adjuster 82 is held on aninner cap 87 attached to the inner side of theouter cap 43 so as to be rotatable around the central axis. The compression-side adjuster 82 extends into therecess 47 and engages with theend piece 81b. Abase portion 82aof the compression-side adjuster 82 is exposed to the outer side from theinner cap 87. In this way, when the compression-side adjuster 82 is rotated from the outer side of thedamper case 15, theend piece 81badvances and retracts in the direction of the central axis C along the compression-side adjuster 82. By doing so, thevalve portion 81vof the compression-side adjustment valve 81 advances and retracts in relation to thethrottle portion 71 to increase and decrease the gap between thethrottle portion 71 and thevalve portion 81v. - The extension-
side adjustment valve 83 includes atubular valve portion 83vwhich is provided in therecess 47 so as to extend toward an opening closer to therecess 47 of thecentral hole 48. Thevalve portion 83vis integrated with the extension-side adjustment valve 83. The compression-side adjustment valve 81 is inserted into the extension-side adjustment valve 83. - The extension-
side adjuster 84 is held on theinner cap 87 attached to the inner side of theouter cap 43 so as to be rotatable around the central axis. The extension-side adjuster 84 extends into therecess 47 and engages with the extension-side adjustment valve 83. Abase portion 84aof the extension-side adjuster 84 is exposed to the outer side from theinner cap 87. In this way, when the extension-side adjuster 84 is rotated from the outer side of thedamper case 15, the extension-side adjustment valve 83 advances and retracts in the direction of the central axis C. By doing so, thevalve portion 83vof the extension-side adjustment valve 83 advances and retracts in relation to the opening of thecentral hole 48 to increase and decrease the gap between thevalve portion 83vand thegap passage 85. - In the damping
force generator 40 having the above-described configuration, the extension-side piston 62 and the compression-side piston 66 are formed of apiston member 75 to be described below. FIG. 6 is a perspective view illustrating a piston member that forms the extension-side piston 62 and the compression-side piston 66.- As illustrated in
FIG. 6 , thepiston member 75 integrally includes innercircumferential walls 75i, outer circumferential walls75oformed on the outer side in the radial direction of the innercircumferential wall 75i, and a plurality ofconnection walls 75wformed at intervals in the circumferential direction so as to extend in the radial direction to connect the innercircumferential walls 75iand the outer circumferential walls75o. - An
insertion hole 75hin which theshaft portion 45 of theholder member 42 is inserted is formed on the inner side of the innercircumferential walls 75i. - A protruding
wall 75mthat protrudes toward the outer side in the radial direction is formed on the outer circumferential surface of the outer circumferential wall75ocontinuously in the circumferential direction. A sealingring 76 that abuts on the inner circumferential surface of thedamper cylinder 29 to seal the space between thepiston member 75 and the inner circumferential surface of thedamper cylinder 29 is provided on the outer circumferential surface of the protrudingwall 75m. - A
first port 77 and asecond port 78 are alternately formed in thepiston member 75 along the circumferential direction between the innercircumferential wall 75iand the outer circumferential wall75o. The first andsecond ports connection walls 75w, adjacent to each other in the circumferential direction. The first andsecond ports end 75aof thepiston member 75 and theother end 75b. For example, thefirst port 77 forms the extension-side inlet port 62tor the compression-side inlet port 66c, and thesecond port 78 forms the compression-side outlet port 62cor the extension-side outlet port 66t. - The
first port 77 has aport inlet 77aprovided closer to oneend 75aand aport outlet 77bprovided closer to theother end 75b. Anotch 75kis formed in the outer circumferential wall75oon the side closer to oneend 75awhereby a port inlet opening (a compression-side port inlet portion)79A that is open to the outer side in the radial direction is formed in thefirst port 77. - The
second port 78 has aport inlet 78aprovided closer to theother end 75band aport outlet 78bprovided closer to oneend 75a. Anotch 75jis formed in the outer circumferential wall75oon the side closer to theother end 75bwhereby a port inlet opening (a compression-side outlet port inlet portion)79B that is open to the outer side in the radial direction is formed in thesecond port 78. - As illustrated in
FIG. 5 , in the dampingforce generator 40 described above, the inner space of thedamper cylinder 29 is partitioned into the first oil chamber S11, the second oil chamber S12, and the third oil chamber S13 by the sealingring 76 of thepiston member 75 that forms the compression-side piston 66 and the sealingring 76 of thepiston member 75 that forms the extension-side piston 62. - The first oil chamber S11 is formed closer to one
end 42aof theholder member 42 than the sealingring 76 of the compression-side piston 66 and communicates with the piston-side oil chamber S1 (seeFIG. 4 ) through the compression-side communication path 102. - The second oil chamber S12 is formed between the sealing
ring 76 of the compression-side piston 66 and the sealingring 76 of the extension-side piston 62 and communicates with the oil storage chamber S3 (seeFIG. 4 ) of thereservoir 30 through thereservoir communication path 107. - The third oil chamber S13 is formed between the sealing
ring 76 of the extension-side piston 62 and theouter cap 43 and communicates with the annular passage101 (seeFIG. 4 ) of thecylinder 11 through the extension-side communication path 105. - The
central hole 48 formed in theholder member 42 is open to the inner space of the first oil chamber S11 at oneend 42aof theholder member 42. - The
passage 64hformed in theintermediate member 64 is open to the inner space of the second oil chamber S12. - Moreover, the
hole 46hformed in thelarge diameter portion 46 of theholder member 42 is open to the inner space of the third oil chamber S13. FIG. 7 is a diagram schematically illustrating the configuration of the shock absorber described above.- As illustrated in
FIGS. 5 and 7 , in a compression-side cycle in which thepiston 12 moves toward the vehicle body in thecylinder 11, oil in the piston-side oil chamber S1 is compressed by thepiston 12. As a result, the oil in the piston-side oil chamber S1 is delivered into the first oil chamber S11 from the compression-side communication path 102 formed in thedamper case 15. - The oil delivered to the first oil chamber S11 flows into the compression-
side inlet port 66cfrom the port inlet opening79A formed in the compression-side piston 66 of themain damper 60 to push and open the compression-side valve 65 provided on the outlet side of the compression-side inlet port 66cand flows toward the second oil chamber S12. In this case, the oil pushes and opens the compression-side valve 65 to pass through the gap between the compression-side valve 65 and the outlet of the compression-side inlet port 66cwhereby damping force is generated. - A portion of the oil delivered to the first oil chamber S11 flows into the
central hole 48 open to oneend 42aof theholder member 42 to pass through the gap between thethrottle portion 71 and thevalve portion 81vof the compression-side adjustment valve 81 and flows into the second oil chamber S12 through thepassage 70 formed in theshaft portion 45 and thepassage 64hformed in theintermediate member 64. In this case, when a portion of the oil passes through the gap between thethrottle portion 71 and thevalve portion 81vof the compression-side adjustment valve 81, damping force is generated. Moreover, by allowing the compression-side adjustment valve 81 to advance and retract with the aid of the compression-side adjuster 82 to adjust the gap between thethrottle portion 71 and thevalve portion 81vof the compression-side adjustment valve 81, it is possible to adjust the damping force generated when the oil passes through the gap between thethrottle portion 71 and thevalve portion 81vof the compression-side adjustment valve 81. - A portion of the oil flowing into the second oil chamber S12 flows into the oil storage chamber S3 through the
reservoir communication path 107 formed in thedamper case 15 in order to compensate for a change in the volume of thepiston rod 13 in thecylinder 11 according to the movement of thepiston 12. Moreover, a remaining portion of the oil flowing into the second oil chamber S12 flows into the compression-side outlet port 62cfrom the port inlet opening79B of the extension-side piston 62 to push and open the compression-sideoutlet check valve 61 and flows into the third oil chamber S13. - The oil flowing into the third oil chamber S13 flows into the rod-side oil chamber S2 through the extension-
side communication path 105, theannular passage 101 of thecylinder 11, and the plurality of oil holes103. - In an extension-side cycle in which the
piston 12 moves toward the wheel in thecylinder 11 according to the upward and downward movement of the wheel, the oil in the rod-side oil chamber S2 is compressed by thepiston 12. As a result, the oil in the rod-side oil chamber S2 flows toward the cylindricalannular passage 101 formed between theinner tube 20 and theouter tube 21 through theoil hole 103 formed in the lower end of theinner tube 20. The oil flowing through theannular passage 101 is delivered toward the third oil chamber S13 of the dampingforce generator 40 through the extension-side communication path 105 formed in thedamper case 15. - The oil delivered to the third oil chamber S13 flows into the extension-
side inlet port 62tfrom the port inlet opening79A of the extension-side piston 62 to push and open the extension-side damping valve 63 provided on the outlet side of the extension-side inlet port 62twhereby damping force is generated. The oil having passed through the gap between the extension-side inlet port 62tand the extension-side damping valve 63 flows toward the second oil chamber S12. - A portion of the oil delivered to the third oil chamber S13 flows into the
recess 47 from thehole 46hformed in thelarge diameter portion 46 of theholder member 42. Moreover, the oil passes through the gap between thegap passage 85 and thevalve portion 83vof the extension-side adjustment valve 83 and flows into the second oil chamber S12 through thegap passage 85, thepassage 70 formed in theshaft portion 45, and thepassage 64hformed in theintermediate member 64. In this case, when a portion of the oil passes through the gap between thegap passage 85 and thevalve portion 83vof the extension-side adjustment valve 83, damping force is generated. Moreover, by allowing theadjustment valve 83 to advance and retract with the aid of the extension-side adjuster 84 to adjust the gap between thegap passage 85 and thevalve portion 83vof the extension-side adjustment valve 83, it is possible to adjust the damping force generated when the oil passes through the gap. - The oil flows from the oil storage chamber S3 into the second oil chamber S12 through the
reservoir communication path 107 formed in thedamper case 15 in order to compensate for a change in the volume of thepiston rod 13 in thecylinder 11 according to the movement of thepiston 12. - The oil having flowed into the second oil chamber S12 passes through the extension-
side outlet port 66tfrom the port inlet opening79B of the compression-side piston 66 to push and open the extension-sideoutlet check valve 67 and flows into the first oil chamber S11. - The oil in the first oil chamber S11 is delivered to the piston-side oil chamber S1 through the compression-
side communication path 102 formed in thedamper case 15. - In the present embodiment, the cross-sectional area A0 of the
reservoir communication path 107 is smaller than the total cross-sectional area A1 of the plurality of compression-side inlet ports 66chaving the compression-side valve 65 that generates damping force. - Moreover, the cross-sectional area A2 of the compression-
side communication path 102 is equal to or larger than the cross-sectional area A1 of the compression-side inlet port 66c. - Furthermore, the cross-sectional area A3 between the compression-
side piston 66 and thedamper cylinder 29 into which the oil flows from the compression-side communication path 102 is equal to or larger than the total cross-sectional area A1 of the compression-side inlet port 66cand is equal to or smaller than the cross-sectional area A2 of the compression-side communication path 102. - Moreover, a total opening area A4 of the plurality of
port inlet openings 79A is larger than the total cross-sectional area A1 of the plurality of compression-side inlet ports 66c. - Due to this, a passage cross-sectional area of a compression-side oil passage system that extends from the piston-side oil chamber S1 to reach the second oil chamber S12 gradually decreases without increasing in the halfway of the passage. Furthermore, since the cross-sectional area A0 of the
reservoir communication path 107 is smaller than the total cross-sectional area A1 of the plurality of compression-side inlet ports 66c, the cross-sectional area A0 of thereservoir communication path 107 is the smallest. - The cross-sectional area A11 of the extension-
side communication path 105 is larger than the cross-sectional area A0 of thereservoir communication path 107. - Furthermore, as illustrated in
FIG. 5 , the cross-sectional area A14 between thedamper cylinder 29 and the extension-side piston 62 is larger than the cross-sectional area A0 of thereservoir communication path 107. - Moreover, the total cross-sectional area A15 of the plurality of compression-
side outlet ports 62cis equal to or larger than the cross-sectional area A14 between thedamper cylinder 29 and the extension-side piston 62. Furthermore, the total opening area A16 of the plurality ofport inlet openings 79B is equal to or larger than the total cross-sectional area A15 of the plurality of compression-side outlet ports 62c. - Furthermore, the cross-sectional area A12 of the
annular passage 101 is equal to or larger than the cross-sectional area A11 of the extension-side communication path 105. Moreover, the total cross-sectional area A13 of the plurality ofoil holes 103 is equal to or larger than the cross-sectional area A12 of theannular passage 101. - In this way, in the compression-side operation, the passage cross-sectional area of the oil passage system that passes through the second oil chamber S12 gradually increases without being narrowed in the halfway of the passage.
- In the above description, the cross-sectional area A0 of the
reservoir communication path 107, the total cross-sectional area A1 of the compression-side inlet port 66c, the cross-sectional area A2 of the compression-side communication path 102, the cross-sectional area A3 between thedamper cylinder 29 and the compression-side piston 66, the total opening area A4 of theport inlet openings 79A, the cross-sectional area A11 of the extension-side communication path 105, the cross-sectional area A14 between thedamper cylinder 29 and the extension-side piston 62, the total cross-sectional area A15 of the compression-side outlet ports 62c, and the total opening areas A16 of theport inlet openings 79B are the cross-sectional areas of the smallest-diameter portions of the passages. - In the
shock absorber 10 of the present embodiment, by setting the cross-sectional area A0 of thereservoir communication path 107 to be smaller than the cross-sectional area A1 of the compression-side inlet port 66c, oil does not easily flow into thereservoir 30 when an excessive input acts during the compression-side operation. In this way, after oil flows from the piston-side oil chamber S1 to the dampingforce generator 40 through the compression-side communication path 102 and damping force is generated in the compression-side inlet port 66c, the oil flows smoothly toward the piston-side oil chamber S1. As a result, theshock absorber 10 can exhibit its original damping characteristics even when oil flows at a high flow speed, for example. - An oil passage system that extends from the piston-side oil chamber S1 to reach the second oil chamber S12 in the compression-side operation is configured so that the cross-sectional area A2 of the compression-
side communication path 102, the cross-sectional area A3 between thedamper cylinder 29 and the compression-side piston 66, the total opening areas A4 of the plurality ofport inlet openings 79A, and the total cross-sectional area A1 of the plurality of compression-side inlet ports 66csatisfy the relation of A2≧A3≧A4≧A1. That is, the passage cross-sectional area of the compression-side oil passage system extending from the piston-side oil chamber S1 to reach the second oil chamber S12 gradually decreases without increasing in the halfway of the passage. Furthermore, since the cross-sectional area A0 of thereservoir communication path 107 is smaller than the total cross-sectional area A1 of the plurality of compression-side inlet ports 66c, the cross-sectional area A0 of thereservoir communication path 107 is the smallest. - In this way, by setting the passage cross-sectional area so as not to increase in the halfway of the flow of oil in the compression-side operation, it is possible to suppress a loss of a passage resistance. In this way, even when oil flows at a high flow speed of 10 m/s, for example, during traveling of motocross or the like, it is possible to prevent generation of damping force which is generated when negative pressure or the like is generated in a portion other than the portion between the compression-
side inlet port 66cand the compression-side valve 65 in which the damping force is to be exhibited. Thus, theshock absorber 10 reliably exhibits its original damping performance. - Moreover, by avoiding formation of a portion in which a passage is narrowed and damping force is generated in a portion other than the portion between the compression-
side inlet port 66cand the compression-side valve 65, when the number of compression-side valves 65 is changed so that the damping characteristics are changed in an opening/closing portion of the compression-side valve 65, a rider can easily detect the change in the damping characteristics. - An oil passage system that extends from the second oil chamber S12 to return to the cylinder-side oil chamber S2 in the compression-side operation is configured so that the cross-sectional area A0 of the
reservoir communication path 107, the cross-sectional area A14 between thedamper cylinder 29 and the extension-side piston 62, the total opening area A16 of the plurality ofport inlet openings 79B, the total cross-sectional area A15 of the plurality of compression-side outlet ports 62c, the cross-sectional area A11 of the extension-side communication path 105, the cross-sectional area A12 of theannular passage 101, and the cross-sectional area A13 of theoil hole 103 satisfy the relation of A0≦A14≦A16≦A15≦A11≦A12≦A13. - In this way, in the compression-side operation, the cross-sectional area of the oil passage system that passes through the second oil chamber S12 gradually increases. Due to this, in the compression-side operation, the oil which has exhibited damping force in the compression-
side inlet port 66cof the compression-side piston 66 does not easily flow into thereservoir communication path 107 and is smoothly discharged from thedamper cylinder 29. FIG. 8 is a diagram conceptually illustrating an oil flow speed distribution when an excessive input acts on the shock absorber in a compression-side cycle and oil flows at a high speed. InFIG. 8 , the thickness of an arrow indicates the flow speed of oil.- As illustrated in
FIG. 8 , by configuring theshock absorber 10 so that the cross-sectional area A0 of thereservoir communication path 107 is the smallest as described above, oil does not easily flow into thereservoir 30 when an excessive input acts during the compression-side operation. In this way, after oil flows from the piston-side oil chamber S1 into the dampingforce generator 40 through the compression-side communication path 102 and damping force is generated in the compression-side inlet port 66c, the oil smoothly flows toward the piston-side oil chamber S1 through an extension-side passage. As a result, theshock absorber 10 can exhibit its original damping characteristics even when oil flows at a high flow speed. FIG. 9 is a diagram illustrating damping characteristics as the relation between stroke and load when an excessive input acts on the shock absorber in the compression-side cycle and oil flows at a high speed.- As illustrated in
FIG. 9 , in the conventional shock absorber which does not have the configuration of the present embodiment described above, the damping characteristics are distorted when the shock absorber operates at a high speed due to an excessive input as indicated by a two-dot chain line inFIG. 9 . In contrast, according to theshock absorber 10 having the configuration of the present embodiment, even when the shock absorber operates at a high speed due to an excessive input, it is possible to suppress deformation of damping characteristics and to obtain satisfactory damping characteristics. - The shock absorber of the present invention is not limited to the embodiment described above with reference to the drawings, and various modifications may occur within the technical scope thereof.
- For example, the configuration of the damping
adjustment portion 80 provided in the dampingforce generator 40 is not particularly limited, and the dampingadjustment portion 80 may be omitted. - Moreover, in the embodiment, although the extension-
side piston 62 and the compression-side piston 66 are formed of thepiston member 75, the present invention is not limited to this. Any one of the extension-side piston 62 and the compression-side piston 66 may be formed alone of thepiston member 75. Moreover, the compression-side inlet port 66conly may include the port inlet opening79A that is open to the outer side in the radial direction. - The entire configuration of the
shock absorber 10 can be changed appropriately. - Beside this, the configurations described in the embodiment may be selected appropriately or changed to another configuration without departing from the gist of the present invention.
Claims (10)
1. A shock absorber comprising:
a cylinder which has an outer tube and an inner tube provided on an inner side of the outer tube in a radial direction at an interval from the outer tube, and in which oil is sealed;
a piston rod of which one end is inserted into the cylinder and the other end is extended outside the cylinder;
a piston which is connected to the one end of the piston rod and is provided in the inner tube so as to be slidable along a central axis direction of the inner tube, and which partitions an inner space of the inner tube into a rod-side oil chamber closer to the piston rod and a piston-side oil chamber on an opposite side to the piston rod;
a damping force generating unit which controls flow of the oil occurring when the piston slides in the inner tube according to a displacement of the piston rod, to generate damping force;
a reservoir that compensates the oil according to a change in advancement volume of the piston rod into the cylinder;
a reservoir communication path through which the damping force generating unit and the reservoir communicate with each other;
a compression-side communication path through which the piston-side oil chamber and the damping force generating unit communicate with each other; and
a compression-side port which is provided in the damping force generating unit, into which the oil flows from the compression-side communication path, and which has a compression-side valve that generates the damping force,
wherein a cross-sectional area of the reservoir communication path is smaller than a cross-sectional area of the compression-side port.
2. The shock absorber according toclaim 1 ,
wherein a cross-sectional area of the compression-side communication path is equal to or larger than the cross-sectional area of the compression-side port.
3. The shock absorber according toclaim 1
wherein the damping force generating unit includes:
a compression-side piston having the compression-side port; and
a damper cylinder that accommodates the compression-side side piston, and
wherein a cross-sectional area between the compression-side side piston and the damper cylinder into which the oil flows from the compression-side communication path is equal to or larger than the cross-sectional area of the compression-side port and is equal to or smaller than the cross-sectional area of the compression-side communication path.
4. The shock absorber according toclaim 3 ,
wherein a compression-side port inlet portion is formed in the compression-side side piston on an inlet side of the compression-side port so as to be open to an outer circumferential surface of the compression-side side piston, and
wherein an opening area of the compression-side port inlet portion is larger than the cross-sectional area of the compression-side port.
5. The shock absorber according toclaim 1 , further comprising:
an extension-side communication path through which the damping force generating unit and an annular passage formed between the outer tube and the inner tube communicate with each other,
wherein a cross-sectional area of the extension-side communication path is larger than the cross-sectional area of the reservoir communication path.
6. The shock absorber according toclaim 5 ,
wherein the cross-sectional area of the annular passage is equal to or larger than the cross-sectional area of the extension-side communication path.
7. The shock absorber according toclaim 5 , further comprising:
an oil hole which is formed in the inner tube so as to allow communication between the annular passage and the rod-side oil chamber,
wherein a cross-sectional area of the oil hole is equal to or larger than the cross-sectional area of the annular passage.
8. The shock absorber according to any one ofclaim 5 ,
wherein the damping force generating unit further includes:
an extension-side piston having an extension-side port into which the oil having flowed from the extension-side communication path into the damping force generating unit flows; and
a compression-side outlet port into which the oil having passed through the compression-side port of the compression-side side piston flows,
wherein a cross-sectional area between the damper cylinder and the extension-side piston is larger than the cross-sectional area of the reservoir communication path.
9. The shock absorber according toclaim 8 ,
wherein the cross-sectional area of the compression-side outlet port is equal to or larger than the cross-sectional area between the damper cylinder and the extension-side piston.
10. The shock absorber according toclaim 8 ,
wherein a compression-side outlet port inlet portion is formed in the extension-side piston on an inlet side of the compression-side outlet port so as to be open to an outer circumferential surface of the extension-side piston, and
wherein an opening area of the compression-side outlet port inlet portion is larger than a cross-sectional area of the compression-side outlet port.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2016-069674 | 2016-03-30 | ||
| JP2016069674AJP6628146B2 (en) | 2016-03-30 | 2016-03-30 | Shock absorber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| US20170284497A1true US20170284497A1 (en) | 2017-10-05 |
| US10145438B2 US10145438B2 (en) | 2018-12-04 |
Family
ID=58094291
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US15/434,633ActiveUS10145438B2 (en) | 2016-03-30 | 2017-02-16 | Shock absorber |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US10145438B2 (en) |
| EP (1) | EP3236104B1 (en) |
| JP (1) | JP6628146B2 (en) |
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| US11635122B2 (en) | 2019-07-18 | 2023-04-25 | Tenneco Automotive Operating Company Inc. | Intake device for a damper having a side collector |
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Also Published As
| Publication number | Publication date |
|---|---|
| US10145438B2 (en) | 2018-12-04 |
| EP3236104B1 (en) | 2020-04-01 |
| JP2017180705A (en) | 2017-10-05 |
| EP3236104A1 (en) | 2017-10-25 |
| JP6628146B2 (en) | 2020-01-08 |
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